Most would think that A would consider this torture. I mean, he's trapped in a box. I'm sure it wasn't his decision to get into the box. And he has no control of getting out when he wants to. Surely, this is not a positive experience for him.
But check it out. He loves it! The girls are having so much fun teaching him how to play. Maybe a little too much fun at his expense, but fun nonetheless. And he adores his sisters.